THE RAFFLES BULLETIN OF ZOOLOGY 2011 THE RAFFLES BULLETIN OF ZOOLOGY 2011 59(1): 61–67 Date of Publication: 28 Feb.2011 © National University of Singapore NEW MYRMOTERAS ANTS (HYMENOPTERA: FORMICIDAE) FROM THE SOUTHEASTERN PHILIPPINES Herbert Zettel Entomological Department, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria Email: [email protected] Daniela Magdalena Sorger Entomological Department, Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria & Department of Biology, North Carolina State University, Raleigh, NC 27695, USA E-mail: [email protected] ABSTRACT. – A key to Philippine species of the formicine ant genus Myrmoteras Forel, 1893 is presented and two new species are described: Myrmoteras (Myagroteras) glabrum, new species from the island of Camiguin and Myrmoteras (Myagroteras) mcarthuri, new species from the island of Leyte. KEY WORDS. – Formicidae, Myrmoteras, Myagroteras, new species, Philippines, Leyte, Camiguin. INTRODUCTION MATERIAL AND METHODS Species of the genus Myrmoteras Forel, 1893 are among Specimens. – Specimens are dry mounted on card squares or the most bizarre ant forms and unique among Formicinae triangles. Examination of specimens was carried out with a by having mandibles that form into a specialized trap-jaw LEICA Wild M10 binocular microscope; measurements were mechanism – a character that, however, has convergently taken at magnifi cations of up to 128×. Digital photographs evolved in other subfamilies (Odontomachus and Anochetus were taken with a Leica DFC camera attached to a Leica in Ponerinae; Dacetini in Myrmicinae). The small Myrmoteras MZ16 binocular microscope with the help of Image Manager ants with cryptic living habits in leaf litter have been rarely IM50 and stacked and processed with Helicon 5.0 and Adobe collected in the past, although more specialized collecting Photoshop 7.0 programmes, respectively. methods have yielded a relatively high species diversity, especially on Borneo and Sulawesi (Agosti 1992). Holotypes are deposited in the Entomological Collection of the University of San Carlos, Cebu City, paratypes in Myrmoteras is the only genus of the tribus Myrmoteratini the Natural History Museum Vienna and in the authors’ Emery, 1895 (Bolton 2003) and has a chiefly Oriental reference collections. distribution from India to the Philippines, Sulawesi, and Lombok of the Lesser Sunda Islands; limited to the east Terminology. – Terminology and method of description by Weber’s Line (Agosti 1992; Tab. 1). Both subgenera, chiefl y follow Moffett (1985). Characters of diagnoses are Myrmoteras s.str. and Myagroteras Moffett, 1985, are not fully repeated in the descriptions. probably monophyletic entities (Moffett 1985). Only Myagroteras is known east of Huxley’s Line (Philippines, Measurements and indices. All measurements are in Sulawesi, Lombok), and two Philippine-endemic species millimetres. have been described in the past: Myrmoteras (Myagroteras) TL Total length. Length of outstretched ant measured williamsi Wheeler, 1919 and Myrmoteras (Myagroteras) from apex of closed mandibles to apex of gaster. insulcatum Moffett, 1985. In this study we add two further HW Head width. Maximum width of head, in full-face species. However, the knowledge on Myrmoteras in the view behind eyes (excluding eyes). Philippines is extremely fragmentary (see Fig. 13), and HL Head length, in full-face view, excluding mandibles, much more specifi c fi eld work with leaf litter sampling is measured at full-face view along midline, from required in order to provide a more complete picture than anterior clypeal margin to posterior margin of occipital we can present now. lobe. 61 Zettel & Sorger: Myrmoteras ants from the Philippines EL Eye length. Maximum diameter of eye. Diagnosis of worker. – Colour mainly dark brown. Dorsum ML Mandibular length. Length of closed mandible of head smooth. Median frontal sulcus prominent. Gap measured in straight line from mandible apex to between clypeus and frons narrow. Labrum not strongly lateral clypeus tooth on the same side as mandible projecting, without long trigger hairs. Mandible with apical being measured, when basal length of mandible shaft part not bent ventrad, with two minute preapical denticles. perpendicular to viewing angle. Disk of pronotum smooth. Dorsum of propodeum strongly MI Mandibular index. ML/HL × 100. convex. Middle tibia strongly dilated, approximately 4.0–4.5 SL Scape length. Length of antennal scape, measured in times longer than wide. straight line, excluding basal condyle. SI Scape index. SL/HW × 100. Description of worker. – Measurements of holotype worker: PW Pronotal width. Maximum width of pronotum in TL 4.48, HW 0.87, HL 0.88, EL 0.57, ML 1.21, MI 137, dorsal view. SL 0.95, SI 109, PW 0.54, WL 1.28. WL Mesosoma length. Diagonal length of alitrunk in lateral view, from frontal-most point of declivitous Measurements of paratype workers: Range of 19 workers: area of pronotum to posterior-most point of apex of TL 4.30–4.72, HW 0.83–0.90, MI 135–141, WL 1.18–1.29. metapleural lobe. Measurements of worker with smallest HW: TL 4.30, HL 0.85, EL 0.53, ML 1.20, MI 141, SL 0.88, SI 106, PW 0.52, WL 1.18. Measurements of worker with largest HW: TAXONOMY OF PHILIPPINE SPECIES TL 4.65, HL 0.91, EL 0.59, ML 1.27, MI 140, SL 0.99, SI 110, PW 0.56, WL 1.27. Key to Philippine species of Myrmoteras (workers and gynes) Colour: Dark brown, posterior half of mesosoma and petiole almost black. (One callow worker with soft integument pale, 1 Head (Fig. 1) and pronotum (Fig. 3) smooth and shiny .... 2 brown and yellow.) Mandibles and palpi yellow. Antennae – Head (Figs. 7, 11) and pronotum (Fig. 9) granulate and dull. brownish yellow. Legs dark brown except bases of tibiae ............................................................................................... 3 light brown and tarsi pale yellowish. 2 Median frontal sulcus distinct (Fig. 1). Body dark brown ..... Structures: Head (Fig. 1) with sparse pilosity, longest hairs ca. ....................................................... M. glabrum, new species – Median frontal sulcus absent. Body dark orange red ............. 0.08 mm long. Frons, temples and vertex smooth and shiny. ......................................................................... M. insulcatum Frons with few faint rugulae anteriorly, median frontal sulcus narrow, neither reaching anterior frons margin nor anterior 3 Posterior face of temple (behind ridge) finely granulate. ocellus. Antennal scrobes indistinct, but anteriomedially Mandible Index 1.45 (Fig. 7). Petiolar node wide (lateral limited by short, curved rugae. Temple with blunt ridge aspect, Fig. 8). Antennomeres 2 and 3 of subequal length (Fig. separating a fl at anterior from slightly convex posterior face. 7) ................................................. M. mcarthuri, new species Clypeus with broad posteromedial elevation, with some – Posterior face of temple (behind ridge) smooth, without any faint rugae, mostly near margins; anterior margin deeply sculpture. Mandible Index 1.30 (Fig. 11). Petiolar node narrow concave. Mandibles long, smooth, dentition see Figure 1. (lateral aspect). Antennomere 2 approximately 1.5 times as long as antennomere 3 (Fig. 11) ....................... M. williamsi Maxillary palp with 6, labial palp with 4 segments. Antenna with moderately slender funiculus, each segment less than twice as long as broad (except long ultimate), antennomere 3 SPECIES ACCOUNTS slightly shorter than antennomere 2 (in holotype, measured at leading edge, 0.82 times). Mesosoma, node and gaster (Figs Myrmoteras (Myagroteras) glabrum, new species 2, 3) smooth and sparsely pilose, longest hairs ca. 0.12 mm (Figs. 1–6, 13) long: Pronotum low and evenly convex, summit virtually level with anterior of mesonotum. Mesonotum with low, Etymology. – The Latin adjective glaber means smooth, and the but distinct rugae, irregularly arranged, individually varying epithet refers to the smooth surface of the whole body. from predominately longitudinal to predominately transverse; with pair of distinct ridges extending from metanotal tubercle Material examined. – Holotype (worker) from the Philippines, forward. Metanotal groove visible as feebly impressed notch Camiguin Island, municipality of Mambajao, barangay Tupsan, in lateral aspect. Meso- and metapleura smooth. Propodeum Macaw Cold Spring, ca. 10 m a.s.l., 09°11'N, 124°46'E, 17 March dorsally smooth, in some individuals a few faint rugae 2010, leg. H. Zettel & C. V. Pangantihon (# 517) (label see Fig. indicated. Middle and hind tibiae strongly dilated, middle 4). tibia of holotype 4.3 times as long as wide. Foretibia slender. Paratypes: 17 workers and 1 alate gyne from the same nest as the Node of petiole slender in lateral aspect. Gaster smooth. holotype. 1 worker from the Philippines, Camiguin Island, west of Mambajao proper, Katibawasan spring area, ca. 350 m a.s.l., 15 Description of gyne. – Measurements of paratype gyne: TL March 2010, leg. H.Zettel & C. V. Pangantihon (# 515). 1 worker 4.62, HW 0.91, HL 0.91, EL 0.58, ML 1.20, MI 131, SL 0.95, from the Philippines, Camiguin Island, municipality of Mambajao, SI 104, PW 0.61, WL 1.30. Length of forewing 2.88. barangay Dagoocan, spring area, c. 350 m a.s.l., 14 February 2007, leg. H. Zettel (# 472). 62 THE RAFFLES BULLETIN OF ZOOLOGY 2011 Colour: Similar to worker, but head lighter than mesosoma, gynes (Fig. 6). Pronotum laterally with faint granulation. more orange brown. Wings pale, veins yellow. Mesoscutum posteromedially with